Checking for problems in my.cnf
If you want to check for errors in the MySQL configuration file my.conf you can start the MySQL daemon from a command line with helpful parameters:
will provide a lot of information about the available parameters.
More useful for diagnosing problems is:
which starts up MySQL with a lot of messages - including diagnostics for any problems in my.cnf.
Of course, the MySQL daemon should not be running when these commands are run. And you may want to restart MySQL afterwards using whatever is the standard technique for the system you are using.